A module construction of a typical TFT-LCD (thin film transistor liquid crystal display) module is illustrated in FIG. 1.
Referring to FIG. 1, an LCD module 1 includes a driving circuit unit 2, an LCD panel 5, and a backlight unit 7.
The driving circuit unit 2 has a plurality of gate driver ICs 6A–6C and source driving ICs 6C–6E for driving a panel 5 and printed circuit boards (PCBs) 3 and 4 to which a variety of circuit components such as a timing controller are attached. The LCD panel 5 has a shape where a liquid crystal is inserted into two glasses between substrates. The LCD panel 5 controls amount of white plane light that is incident from the backlight unit 7 to transmit pixels, serving to display color images in response to each pixel signal voltage inputted from the driving circuit unit 2. The backlight unit 7 has a lamp 8 and a reflex plate 9 and makes plane light having a unit bright from a fluorescent lamp 8 acting as a light source.
As well known to those skilled in the art, the LCD panel 5 includes gate lines and source lines that are intersected in a lattice shape. A pixel is coupled to a gate line and a data line. For example, an LCD panel for a VGA (video graphics array) mode includes 640×480 pixels, and an LCD panel for an XGA (extended graphics array) mode includes 1024×768 pixels. To drive a number of pixels, a gate driver IC and a source driving IC have a number of output pins. The number of these output pins is dependent upon the resolution of the LCD panel 5 that the IC employs. Since an IC cannot have innumerable output pins, the LCD module 1 uses a plurality of ICs that are serially connected. For example, since the LCD panel for the VGA mode has 640 source lines, source driving ICs having 320 output pins must be serially connected by two or a source driving IC having 640 pins may be used.
Generally, a semiconductor integrated circuit is tested by assigning test pins of a test device to all input/output pins in a one-on-one relationship. However, there are required a number of test pins to test integrated circuits having many input/output pins like the foregoing integrated circuits for driving an LCD, i.e., a gate driver IC or a source driving IC.
With scale-up and high definition of LCD panels, the number of pins installed at driving ICs is increasing and a pitch between pins is decreasing. This leads to a difficulty in increasing the number of pins of a test device as pins of the semiconductor integrated circuit increase in number.